Method of operating pressurized storage system



3,105,358 METHOD OF OPERATING PRESSURIZED STORAGE SYSTEM Original Filed Jan. 3, 1956 E. E. REED s Sheets-Shee t 1 Oct. 1, 1963 5 D v, M E R R W m IE T O m A 6 4 v 6 l T mm 1 l 1 4 H W mm A a F 6 0 w 0 a n5 .7.

b l I u F rli'wwikww IJ Oct. 1, 1963 E. E. REED 3,105,358

METHOD OF OPERATING PRESSURIZED STORAGE SYSTEM Original Filed Jan- 3, 1956 s Sheets-Sheet 2 i its FIG. 2

INVENTOR. E.E. REED ATTOR/VE s Oct. 1, 1963 Original Filed Jan. 5, 1956 E. E. REED 3,105,358

METHOD OF OPERATING PRESSURIZED STORAGE SYSTEM 3 Sheets-Sheet 3 INVENTOR. I as. REED A 7' TORNEVS United States Patent 3,105,358 METHOD OF OPERATING PRESSURIZED STORAGE SYSTEM Edwin E. Reed, Bartiesviiie, Okla, ass'gnor to Phillips ietroleum Company, a corporation of Delaware Uriginal application Jan. 3, 1956, Ser. No. 556,853, new Patent No. 3,096,149, dated Oct. 31, 1961. Divided and this application Jan. 3, 1961, Ser. No. 80,349 14 Claims. (Cl. 6l.5)

This invention relates to an improved pressurized storage system and method of operating same.

This application is a division of my copending application Serial No. 556,853, filed January 3, 1956 and now Patent No. 3,006,149.

Constantly expanding production of liquefiied petroleum gas has created a definite problem in providing suitable storage facilities for this material. Due to the high vapor pressure of liquefied petroleum gas, particularly propane, the cost of storage in surface equipment, such asrsteel tanks, becomes excessive due to the massive construction required to withstand the vapor pressure of the stored material in a safe manner. The problem becomes extremely acute where it is necessary to store large quantities of such materials during the cit-season. In addition to the expense involved, the use of steel tanks is limited by shortages in production.

In order to overcome some of these difiiculties, it has been proposed to store liquefied petroleum gas in porous water bearing formations, in water-leached caverns in salt formations or in abandoned mines in impermeable shale or in limestone formations. Further, underground concrete storage tanks and buried sections of pipe have been used to a limited extent in the storage of liquefied petroleum gas.

In my copending application, Serial No. 348,344, filed April 13, 1953, entitled Pressurized Storage System and Method of Operating, now Patent No. 2,901,889, there is disclosed and claimed an underground storage system for liquefied petroleum gas which is capable of storing extremely large quantities of this material at a very small cost. The present invention relates to a method and means for sealing such a system against product losses during equipment changes and is an improvement over the'invention disclosed and claimed in my said copending application. The storage system of my said copending application and the storage system and method of operating given herein are not limited to the storage of liquefied petroleum gas, but are applicable to the storage or' my liquefiable gas such as ammonia, carbon dioxide, and the like. Further, the present invention is not necessarily limited to underground storage systems and can be employed where steel tanks are used as the pressurized containers.

There are many methods of removing liquefied gas from a storage container. For example, it is well known that a liquefied gas can be forced from a chamber by introducing compressed gas above the liquid. In other instances, displacement by a second non-contaminating liquid of greater density can be employed. One method, and a more generally preferred method, for removing a liquefied gas from storage is by means of a centrifugal pump. The pump is usually contained within the pressurized container and can be one wherein the motor driving the pump is also submerged, or of the type driven by a rotating shaft attached to a motor outside of the container. It is recognized that such pumps will have to be pulled from the container from time to time for repair or replacement. To do this, some means must be provided to prevent the loss of large quantities of vapor from the container. There is disclosed in my said copending application Serial No. 348,344, mentioned above,

Patented Oct. 1, 1963 an apparatus and method to insure that the container can be tightly sealed during the time the pump is being operated or being inserted or withdrawn.

In particular, there is disclosed and claimed in said Serial No. 348,344, a spring-operated, n'ormally-closd valve at the bottom of a casing providing communication between the surface of the earth and the caverns. The valve stem of saidvalve is displaced by the pump body disposed within said casing, and thereby the valve is opened when the pump is lowered into operating position. Accordingly, when the pump body is raised the valve closes, thereby sealing the cavern or storage container.

1 have found that water flooding of the casing, in which the pump is normally disposed, during the removal and reinstallation of the pump is a desirable safety feature. Water flooding of said casing has the advantages of (1) providing a higher pressure in the casing than in the storage container, and, (2) a decelerator for the pump should it be dropped while being reinstalled. From a safety standpoint, when inflammable liquids are stored in the storage container, Water flooding has the advantage of completely removing the inflammable liquid and vapors thereof during the pump withdrawal and reinstallation. However, the use of water flooding in conjunction with the bottom hole valve of my above referred to copending application Serial No. 348,344, is not completely satisfactory because the valve will open when the head of water in the casing exceeds the container pressure and allow water to enter the storage container. 1 have now developed a two-seated shutoff and check valve which can be employed as a bottom-hole valve and which eliminates the above described dilficulty. Said new valve,

discussed further hereinafter, is one of the subcombinations of the present invention.

An object of this invention is to provide an improved pressurized storage system and method of operating same. Another object of this invention is to provide an improved underground storage system for storing liquefied gases under pressure. A further object of this invention is to provide an underground storage system capable of storing liquefied gases having a high vapor pressure for an extended period with a minimum of operating difficulties. Still another object of this invention is to provide a method for Withdrawing and reinstalling a pump in a pressurized storage container without loss of vapors of the products stored therein. A further object of this invention is to provide an improved shutoff and check valve. Still another object of this invention is to provide an improved means for sealing one tubing within another tubing. Still other aspects, objects, and advantages of the invention will be apparent to those skilled in the art upon reading this disclosure.

Thus according to the invention, there are provided a method and apparatus for withdrawing a pump from a pressurized container without loss of pressure from said container. The container is provided with a conduit extending through a boundary thereof and closably communicating with the container. A submersible pump is positioned within the conduit adjacent the region of communication of said conduit with said container. When it is desired to remove the pump, said pump is moved, as by lowering, to a non-operating position within the conduit. Concomitantly with the moving of the pump the conduit is closed oft" from the container. The pressure in the conduit is released and said conduit is filled with an inert liquid, such as water, so as to maintain said conduit in a closed off condition. Thereafter the pump is withdrawn. After the pressure is released from the conduit the contents thereof may be vented off or said contents can be displaced with said inert liquid as the conduit is filled.

When reinstallation of the pump is desired said pump, suspended from a discharge tubing connected thereto, is run into the conduit to an operating position therein adjacent the region of communication of said conduit with said container. Pressure between the conduit and the container is equalized and water is pumped from the conduit. As the head of water in the conduit is decreased the valve Will concomitantly open and provide communication between the conduit and the container. An alternative procedure is to lower said pump to a non-operating position, pump the water from the conduit, and then raise the pump to an operating position, which raising will concomitantly open the conduit in communication with the container.

Further according to the invention, there is provided apparatus for carrying out the method of the invention and attaining the above mentioned objects. The apparatus of the invention includes a combined shutoff and check valve, means for sealing one tubing within another tubing, and an improved pressurized storage system.

While water has been given as an example of an inert liquid, other liquids can be employed. Any liquid which is inert, i.e., non-reactive under condition of use with the material being stored, has a specific gravity greater than said stored material, and is substantially immiscible with said stored material, can be used. Non-inflammable liquids are preferred. Water is the presently preferred liquid and is used herein for illustrative purposes.

FIGURE 1 is a vertical elevation, partially in section, of part of an underground storage system constructed in accordance with this invention.

FIGURE 2 is a sectional view, partially in elevation, of a shutoff and check valve according to the invention.

FIGURE 3 is another view of the valve shown in FIG- URE 2.

FIGURE 4 is an elevation, partly in section, of the well head apparatus employed at the surface of the earth for sealing the underground storage cavern.

FIGURE 5 is a sectional view, partially in elevation, of a slip joint sealing means employed to seal one tubing within another tubing.

FIGURE 6 is a disassembled isometric view of a split bushing which forms a part of the apparatus illustrated in FIGURE 5.

Referring now to the drawings, the invention will be more fully explained as employed in connection with the storage of liquefied petroleum hydrocar bons'such as propane and/or butane. In the drawings, like reference numerals are employed to denote like elements. In FIG- URE 1, there is shown a cavern 10 connected by means of a vertical shaft 11 to the surface of the ground. Cavern 10 can comprise more than one cavern and said caverns can be connected by suitable tunnels. Said caverns can be constructed in a number of different ways as illustrated in the copending application of L. P. Meade, Serial No. 314,541, filed October 13, 1952 and now abandoned. Said shaft 11 extends below the floor of cavern 10 to form a sump or well 12 below the floor of said cavern. A metal liner 13 lines the shaft from the surface of the earth to the roof of the cavern and is held firmly in place by means of cement 14. A well head 15 closes liner 13 and seals the contents of the cavern from the atmosphere. Access lines 16 and 17 provide communication through the side of liner 13 below the seal point of well head 15. Valves 13 and 19 control said access lines. A first conduit or tubing 24 is suspended from well head 15 and extends through cavern 11 into well or sump 12. Surrounding said tubing 20 is an outer tubing 21 which is attached at its upper and lower ends to said tubing 20 as shown. Said outer tubing 21 contains a series of perforations 22 near the bottom end thereof and another series of perforations 23 near the top end thereof. The lower end of tubing 20 has a series of perforations 24, below the valve 25, which perforations extend to a point higher than the perforations 2 in outer pipe 4.. Perforations 22, 23, and 24 together with the outer tubing 21 comprise collectively a pump inlet means which is disclosed and claimed in ccpending application Serial No. 441,244, filed July 6, 1954, by E. S. Miles and E. W. Porter and now Patent No. 2,884,761.

Mounted above well head 15 is a slip joint assembly, denoted generally by 26, which provides means for sealing a discharge tubing 27 within said first tubing 2%. Said slip joint assembly is described further hereinafter. A pump 28 is suspended from tubing 27, which serves as a discharge tubing for said pump, and is disposed within tubing 20 at a point adjacent the ergion of communication of said tubing 24 with cavern 1i). Said pump 2% comprises three main parts, i.e., a lower part or motor, a protector unit mounted above said motor, and a top unit which comprises the pumping unit itself. However, herein and in the claims, the term pump, unless othe wise specified, will be employed generically to include all three parts of said pump, as well as other suitable pumps which can be employed in this service. Submersible pumps of this type are well known to those skilled in the art. Although not shown, it will be understood that a cable 29 extends from the motor section of said pump, within the inner space between tubings 2'7 and Ztl, to the surface of the earth as shown in FIGURES 4 and 5. Said cable attaches to a source of electric power (not shown) for energizing said motor. Said cable has been omitted from FIGURE 1 for the sake of clarity.

FIGURES 2 and 3 illustrate one modification of the improved valve of the invention. As shown in FIGURE 2, said valve is closed at its upper seat. Said valve, de-

noted generally by 25, comprises a valve'body 36 which v can be divided into two parts and sealed as shown at 37. However, it will be understood that said valve body can be comprised of one continuous pieceof cylindrical tubing. As shown here, valve body 36 is connected to the lower endof tubing 2% by welding as at 38. Obviously other means such asv threads can be employed in connecting said valve body and said tubing. Likewise, said valve body 36 can be an extension of tubing 2%. Mounted within valve body 36 and secured to the inner wall thereof is a first or lower valve seat 39. Spaced apart from and also secured to the inner wall of said valve body is a second or upper valve seat 49. Spaced apart from said upper valve seat 41 on the opposite side thereof from said valve seat 39 is a perforated guide member 41 which is secured to the inner wall of said valve body 36. Disposed within the chamber between said valve seats 39 and 40 is a valve head 42. Said valve head is comprised of a first or upper disc 43 and a second or lower disc 44, separated by a spacer plate 45. Spacer plate 45 is a fiat metal disc having a perforation in the center thereof and is provided with a lip 52 extending above the surface on both sides at the outer circumference thereof. Discs 43 and 44 are flat metal discs having a perforation in the center thereof. Each of said discs is provided with an outer beveled edge 51 adapted to cooperate with and seat in the corresponding beveled seating surface in valve seats 39 and 40. Said discs are recessed at their outer circumference on the side opposite said beveled edge 51 for receiving O-rings 46 between said beveled edge and said lip 52. Said O-rings are prefer-ably fabricated from a suitable resilient material such as an oil-resistant rubber, for example neoprene. Said valve head 42 by being provided with the upper and lower discs 43 and 44- is thus adapted to seat in either valve seat 39 or valve seat 40. The split construction of the valve head together with the resiliency of O-rings 46 provide a very desirable flexibility in fabrication and operation of the valve and it is not necessary to machine and position the valve seats 39 and 40, with respect to each other, with the accuracy which would otherwise be necessary if valve head 42 were otherwise constructed, as for example a one piece disc. It is to be noted there is a double seal between the beveled edge seating surfaces of valve seats 39 and 4t}.

and the valve head 42, i.e., there is a metal to metal seal between beveled edges 51 and said beveled edge seating surfaces of valve seats 39 and 4t), and a rubber to metal seal between O-rings 46 and said seating surfaces. Thus small pieces of foreign matter in valve seats 39 and 49 will not prevent valve head 42 from effecting a seal.

One end of a valve shaft 47 extends through the perforations in the members of valve head 42 which are held in their illustrated assembled positions by means of nut 43 and washer 53. The other end of valve shaft 47 extends through valve seat 4 3, the perforation in guide member 41, and terminates with a combined contact member and spring guide 43. Coil springs 49 are mounted around valve shaft 47 between contact member 48 and a spring guide 54 mounted on guide member 41. A single coil spring can be employed if desired. Spring guides 5:) are employed to maintain said springs in proper vertical alignment.

It is a feature of the invention that when springs 49 are compressed, spring guides 50 and 54, together with combined contact member and spring guide 48, will form a solid stack when valve head 42 has moved a suflicient distance to seat in valve seat 39. Valve shaft 47 backs up into space 55 in combined contact member and spring guide 48. All compression loading is thus taken off valve shaft 47 and cannot be transmitted to valve seat 39. For example, in a vertical installation, should the pump be lowered too far or dropped during reinstallations (described further hereinafter) the weight or force will be borne by guide member 41. The advantage of this feature will be readily appreciated by those skilled in the art.

FIGURE 3 shows the valve head 42 of FIGURE 2 disposed in an open position between valve seats 39 and 4t Said valve has been opened by lowering pump 28 into contact with contact member 48.

FIGURE 4 illustrates in detail the well head assembly employed to seal the liner 13, tubing 2%), and tubing 27. Liner 13 is connected to well head by threaded engagement as shown. If desired, a seal weld can be provided between said liner 13 and well head 15. Tubing 26 is suspended within well head 15 by means of threaded engagement with hanger 56. Hanger 56 is sealed to well head 15 by means of the O-rings shown or other suitable sealing means. Flange 57 is removably attached to flange 58 of well head 15. Said flanges are sealed by means of an O-ring therebetween as shown or other suitable sealing means. Mounted within and sealed to flange 57 is an outer tubing or casing 59, a flange 6t sealed to its other end. Discharge tubing 27 extends upwardly through tubing 28, casing 59, and is attached by means of a coupling 61 to a pipe 62 which extends through flanges 6'3 and 6t). Said pipe 62 is attached as by welding, at its circumference to flange 63 but extends freely through flange 6!). Inner cylindrical member 64 is sealed to and extends downwardly from flange 63 and surrounds said pipe 62. The lower end of cylindrical member 64 termimates in shoulder 79 (FIGURE 5) which bears against the inner wall of casing 59 and is provided with suitable sealing means such as the O-ring shown. Cable 29 extends upwardly within the inner space between tubing 27 and tubing 2%) and out through stufling box 65. While a coupling 61 g pipe 62 Within casing 59, it will be realized by those skilled in the art that if desired tubing 27 could be extended upwardly through flanges 69 and 63 as described to take the place of pipe 62 within casing 59 and the coupling effected above flange 63. However, the use of coupling 61 and the pipe 62 provides a convenient short length of equipment which is more conveniently handled. Similarly, pipe 62 could be extended to a lower level and connect with tubing 27 in well head 15 or lower. However, it is usually more convenient to make the connection between pipe 62 and tubing 27 within casing 59 as shown. Flange 66 is attached to the upper end of pipe 62. A

'valve seat 46 until said 6 suitable flanged valve 67 is attached to flange 66. A suitable discharge pipe 34 (FIG. 1) is attached to the upper end of valve 67 for conducting liquid pumped rom the cavern to any desired point.

FIGURES 5 and 6 illustrate in detail the slip joint assembly which forms one subcombination of the invention. Said slip joint assembly was shown generally in FIGURE 4. It will be noted that a split bushing or spacer 71 is provided between the flanges 6t and 63. Said split bushing or spacer is shown in detail in FIGURE 6. Said bushing or spacer comprises two members 71a and 71b. Said members each have a lapped or other machine surface 72 at their interface and when drawn together by means of bolt members 73 and 74- form a sealed engagement at said interface. O-rings 75 and 76 provide'a sealing means between said spacer 71 and the flanges 60 and 63. The position of cable 29 is shown clearly in FIGURE 5. it will be noted that the metal sheathing has been stripped from said cable at the portion thereof which passes through stufling box 65. Stufling box 65 is a conventional packing gland assembly and any type of suitable packing can be employed therein. A vent 77 controlled by valve 78 extends from casing 59 at a point above the highest point of shoulder 79 of cylindrical member 64. Said vent thus provides means for venting the space between flange 63 and the lower end 79 of cylindrical member 64 before disassembling the apparatus.

It will be understood that all cooperating flanges such as flanges 575S, 6-8-63, 66 and valve 67, are held together in their assembled positions by means of suitable bolts and nuts. Said bolts and nuts have not been illustrated so as to simplify the drawings.

In assembling and operating the apparatus, well head is placed on liner l3 and tubing 26', having outer tubing 21 positioned thereon as described, is lowered through shaft 11 and into well 12. It will be understood that the portion of tubing 20 having outer tubing 21 thereon is assembled at the surface prior to lowering in the shaft and the remainder of tubing 20' is lowered section by section until it has reached the desired position in well 12. Hanger 56 is then installed on the upper end thereof and the seal is effected between hanger 56 and the well head 15. It will be understood that valve 25 is attached to the lower end of tubing 20, which valve 25 is normally closed so that once tubing 29 is inserted and sealed into well head 15 no material can pass through tubing 21' to the surface or between said tubing and liner l3. Casing 59 having flanges 57 and 6% on the lower and upper ends respectively is then attached to flange 58 of well head 15. Tubing 27, having pump 28 secured to the lowermost section thereof, is lowered through casing 59, section by section, until the approximate proper length has been installed. While the upper end of tubing 27 is still above flange 69, pipe 62 which extends through flange 63 but is attached to said flange 63 at its outer circumference is attached to the upper end of said tubing 27 by means of coupling 61. It will be remembered that cylindrical member 64 is also attached to flange 63 and extends downwardly from the under side of said flange. The assembled tubing 27, pipe 62, and flange 63 is then lowered until the pump 25 has reached its approximate normal operating position. At this time, split bushing 71 is installed around pipe and the pump is lowered to its normal operating posi- The lowering of sa1d pump to its normal operating position will concomitantly open valve 25 through the action of the lower end of pump 28 on contact plate 48 which moves valve head 42 downward from upper valve head 42 is disposed in the chamber between said valve seat 40 and valve seat 39. stored therein. Said material can be introduced through lines 16 or 17. Any suitable type of filling mechanism can be employed at the surface of the earth for introducing the liquid to be stored into lines 16 or 17.

When it is desired or necessary to remove the pump for service, the vent 77 is checked by opening valve and any pressure which may have accumulated in the above seal 79 is vented to'the atmosphere. Flange d3 is then raised sufliciently to permit the removal of split bushing 71. After removal of said bushi. g, is lowered until it abuts flange 6% which lowering will concomitantly close valve 25 by moving valve head 22 into contact with lower valve seat 39. The contents of casing 29 are then vented through lines or 31 to the atmosphere. After venting the contents, said casing 21 is filled with water through either lines 3% or 31. Thereupon, flange 63 is raised until the coupling 61 clears flange 6t). Coupling 61 is uncoupled, and pipe at, flange 63, etc. are moved out of the way, tubing 27 is then raised section by section until the has been completely withdrawn from tubing 20. Alternative to venting the contents of tubing 2e after valve 25 has been closed at its lower position, said contents can be displaced by water admitted through line 31. The entering water will cause the lighter hydrocarbons to be floated upwardly said lighter hydrocarbons can be removed through line 3%, or if desired, through a higher connection in casing 559 (not shown). i

It is to be noted that the hydrostatic head of water in casing 20 holds the valve head 42 against lower valve seat 39 thus maintaining said valve in a closed position during the time the pump is being withdrawn and is removed from the hole. If by some circumstance the water head should be lost or the pressure in cavern it} should exceed said hydrostatic head of .water, then valve head 122 will be forced upwardly against upper valve seat and the valve is still maintained in a closed position. Thus my invention not only eliminates inflammable vapors from the tubing 2% during the pump removal and reinstallation operations but it also provides the additional safety feature of the check valve, because valve 25' is normally closed at its upper seat and will close at said upper seat due to the action of spring 49 when the valve is not held open.

When the pump is reinstalled, pump 25, attached to the lower end of tubing 27, is lowered through casing 59 of slip joint assembly 2-6 until the approximate proper length has been installed. Pipe 62, flange es and cylindrical member 64 are installed as previously described and the assembly is lowered to the approximate normal operating position of pump 25. At this time, the pressure within the cavern and the pressure within tubing 2%} are equalized by means of lines 16, 32 and 31. it will be remembered that equalization is possible because seal 79 by hearing on casing 59 seals tubing 29. After the pressures have been equalized, split bushing 71 is installed as previously described, the pump is lowered to its normal operating position, and the water in casing 20 is pump-e out through lines 62, valve 33 and line 3 When the head of water in casing 23 becomes less than the pressure in cavern 10 plus the force of spring 49, valve 25 will open and admit liquid from cavern it} into casing 2 2'. At this point a mixture of water and propane will be discharged by the pump. Said mixture of water can be discharged through line 34 to any kind of conventional separating means (not shown) at the surface of the earth. When efiiuent from said separating means shows all of the water has been removed the propane stream can then be switched to surface storage or other means as desired.

An alternate procedure in reinstalling the pump 23 is to lower said pump to its bottom position after pipe 62, flange 63, and cylindrical member 64 have been installed. Said lowering to the bottom position will concomitantly close valve 25 by moving valve head 42 into contact with lower valve seat 39. All the water in casing 29 is then pumped out. The pressure in casing 2e and the pressure in cavern 10 are then equalized as previously described. Flange 63 is then raised sulficiently to permit insertion of sees split bushing '71, which raising will concomitantly open valve 25. Flange 63 is then lowered onto the bushing and pump 23 is now in its normal operating position.

The invention is not limited to employing a well or sump 12 illustrated in FIGURE 1. If desired, said wall or sump can be omitted in which case tubing 2% would only extend to a point near the bottom of cavern Herein and in the claims, unless otherwise specified, the term bottom region is employed generically to include the bottom region of cavern lit and any point within sump 12.

As will be understood by those skilled in the art, various other modifications of the invention can be made in the light of the foregoing disclosure and discussion without departing from the spirit or scope of the said invention.

1 claim:

1. A method for withdrawing a pump from a pressurized container without loss of pressure therein, said container being provided with a conduit extending through a boundary thereof and closably communicating with said container, said pump being disposed in an operating position within said conduit adjacent the region of communication of said conduit with said container, which method comprises: moving said pump to a normally non-operating position within said conduit and concomitantly causing said conduit to be closed off from said container; displacing the contents of said conduit with an inert liquid to provide a static head pressure in said conduit greater than the pressure in said container and maintain said conduit in said closed ofi condition; and thereafter withdrawing said pump from said conduit.

2. A method for withdrawing a pump from a pressurized underground storage system without loss of pressure therein, said system being provided with a conduit extending from the surface of the earth into a region near the bottom of said system, said conduit closably communicating with the remainder of said system, and said pump being disposed in an operating position within said conduit adjacent the region of communication of said conduit with said system, which method comprises: lowering said pump to a normally non-operating position within said conduit and concomitantly causing said conduit to be closed oil from said system; displacing the contents of said conduit with an inert liquid to provide a static head pressure in said conduit greater than the pressure in said container and maintain said conduit, in said closed off condition; and thereafter withdrawing said pump from said conduit.

3. A method for withdrawing fro-m and reinstalling a pump into a pressurized container without loss of pressure therein, said container being provided with a conduit extending through a boundary thereof and closably communicating with said container, said pump being disposed in an operating position within said conduit adjacent the region of communication of said conduit with said container, which method comprises: moving said pump to a normally non-operating position within said conduit and concomitantly causing said conduit to be closed oil from said container; displacing the contents of said conduit with an inert liquid to provide a static head pressure in said conduit greater than the pressure in sm'd container and maintain said conduit insaid closed off condition; withdrawing said pump from said conduit; reinserting said pump into said conduit to said operating position within said conduit; equalizing the pressure within said conduit and the pressure within said container; and pumping said liquid from said conduit and concomitantly causing said conduit to be opened into communication with said container.

4. A method for withdrawing from and reinstalling a pump into a pressurized container without loss of pressure therein, said container being provided with a conduit extending through a boundary thereof and closably communicating with said container, said pump being disposed in its normal operating position within said conduit adjacent the region of communication of said conduit with said container, which method comprises: moving said pump to a normally non-operating position within said conduit and concomitantly causing said conduit to be closed off from said container; displacing the contents of said conduit with an inert liquid to provide a static head pressure in said conduit greater than the pressure in said container and maintain said conduit in said closed ofi condition; withdrawing said pump from said conduit; reinserting said pump into said conduit to said normally non-operating position within said conduit; pumping said liquid from said conduit; and then moving said pump to said normal operating position and concomitantly causing said conduit to be opened into communication with said container.

5. A method for withdrawing from and reinstalling a pump into a pressurized underground storage system without loss of pressure therein, said system being provided with a conduit extending from the surface of the earth into a region near the bottom of said system, said conduit closably communicating with the remainder of said system, and said pump being positioned in its normal operating position within said conduit adjacent the region of communication of said conduit with said system, which method comprises: lowering said pump to a normally nonoperating position within said conduit and concomitantly causing said conduit to be closed off from said system; displacing the contents of said conduit with an inert liquid to provide a static head pressure in said conduit greater than the pressure in said container and maintain said conduit in said closed off condition; thereafter withdrawing said pump from said conduit; reinsertin" said pump into said conduit to said normal operating position in said conduit; equalizing the pressure within said conduit and the pressure within said system; and pumping said liquid from said conduit and concomitantly causing said conduit to be opened into communication with said system.

6. A method for withdrawing a pump from a precsurized container without loss of pressure therein, said container being provided with a conduit extending through a boundary thereof and cl Sably communicating with said container, said pump being disposed in an operating position within said conduit adjacent the region of communication of said conduit with said container, which method comprises: moving said pump to a normally nonoperating position within said conduit and concomitantly closing off said conduit from said container; releasing the pressure within said conduit; filling said conduit with an inert liquid to provide a static head pressure in said conduit greater than the pressure in said container and maintain said conduit in said closed 01f condition; and thereafter withdrawing said pump from said conduit.

7. The method of claim 6 wherein a liquefied petroleum gas is stored Within said container and said inert liquid is water.

8. A method for withdrawing a pump from a pressurized container, having a normally gaseous material therein, without loss of pressure therein, said container being provided with a conduit extending through a boundary of said container and closably communicating with said container, said pump being disposed in an operating position within said conduit adjacent the region of communication of said conduit with said container, which method comprises: moving said pump to a normally non-operating position within said conduit and concomitantly closing off said conduit from said container; releasing the pressure within said conduit; venting the contents of said conduit; filling said conduit with an inert liquid to provide a static head pressure in said conduit greater than the pressure in said container and maintain said conduit in said closed off condition; and thereafter withdrawing said pump from said conduit.

9. The method of claim 8 wherein a liquefied petroleum gas is stored within said container and said inert liquid is water.

10. A method for withdrawing a pump from a pressurized container without loss of pressure therein, said container being provided with a conduit extending through a boundary of said container and closably communicating with said container, said pump being disposed in an operating position within said conduit adjacent the region of communication of said conduit with said container, which method comprises; moving said pump to a normally non-operating position within said conduit and concomitantly closing off said conduit from said container; releasing the pressure within said conduit; displacing the contents of said conduit with an inert liquid to provide a static head pressure in said conduit greater than the pressure in said container and maintain said conduit in said closed off condition; and thereafter withdrawing said pump from said conduit.

11. A method for withdrawing from and reinstalling a pump into a pressurized container without loss or" pressure therein, said container being provided with a conduit extending through a boundary thereof and closably communicating with said container, said pump being disposed iin an operating position within said conduit adjacent the region of communication of said conduit with said container, which method comprises: moving said pump to a normally non-operating position within said conduit and concomitantly closing oif said conduit from said container; releasing the pressure Within said conduit; filling said conduit with an inert liquid to provide a static head pressure in said conduit greater than the pressure in said container and maintain said conduit in said closed off condition; withdrawing said pump from said conduit; reinserting said pump into said conduit to said operating position within said conduit; equalizing the pressure within said conduit and the pressure within said container; and pumping said liquid from said conduit and concomitantly opening said conduit into communication with said container.

12. A method for withdrawing from and reinstallin a pump into a pressurized container without loss of pressure therein, said container being provided with a conduit extending through a boundary thereof and closably communicating with said container, said pump being disposed in its normal operating position within said conduit adjacent the region of communication of said conduit with said container, which method comprises: moving said pump to a normally non-operating position with-in said conduit and concomitantly closing off said conduit from said container; releasing the pressure within said conduit; filling said conduit with an inert 'liquid to provide a static head pressure in said conduit greater than the pressure in said container and maintain said conduit in said closed off condition, withdrawing said pump from said conduit; reinserting said pump into said conduit to said normally non-operating position within said conduit; pumping said liquid from said conduit; and then moving said pump to said normal operating position and concomitantly opening said conduit into communication with said container.

13. A method for withdrawing a pump from a pressurized underground storage system without loss or" pressure therein, said system being provided with a conduit extending from the surface of the earth into a region near the bottom of said system, said conduit closably communicating with the remainder of said system, and said pump being disposed in an operating position within said conduit adjacent the region of communication or" said conduit with said system, which method comprises: lowering said pump to a normally no -operating position within said conduit and concomitantly closing oif said conduit from said system; releasing the pressure within said conduit; filling said conduit With an inert liquid to provide a static head pressure in said conduit greater than the pressure in said container and maintain said conduit in said closed off condition; and thereafter withdrawing said pump from said conduit.

14. A method for Withdrawing from and reinstaliing a pump into a pressurized underground stora e system without loss of pressure therein, said system being provided with a conduit extending from the surface of the earth into a region near the bottom of said system, said conduit closably communicating with the remainder of said system, and said pump being positioned in its normal operating position within said conduit adjacent the region of communication of said conduit with said system, which method comprises: lowering said pump to a normally non-operating position Within said conduit and concomitantly closing off said conduit from said system; releasing the pressure within said conduit; filling said conduit with an inert liquid to provide a static head pressure cases 12, in said conduit greater than the pressure in said container and maintain said conduit in said closed oii condition; thereafter withdrawing said pump from said conduit; reinserting said pump into said conduit to said normal operating position in said conduigequalizing the pressure within said conduit and the pressure within said system; and pumping said iiquid from said conduit and concomitantly opening said conduit into communication with said system.

References Qited in the file of this patent UNITED STATES PATENTS 

1. A METHOD FOR WITHDRAWING A PUMP FROM A PRESSURIZED CONTAINER WITHOUT LOSS OF PRESSURE THEREIN, SAID CONTAINER BEING PROVIDED WITH A CONDUIT EXTENDING THROUGH A BOUNDARY THEREOF AND CLOSABLY COMMUNICATING WITH SAID CONTAINER, SAID PUMP BEING DISPOSED IN AN OPERATING POSITION WITHIN SAID CONDUIT ADJACENT THE REGION OF COMMUNICATION OF SAID CONDUIT WITH SAID PUMP TO A NORMALLY NON-OPERATCOMPRISES: MOVING SAID PUMP TO A NORMALLY NON-OPERATING POSITION WITHIN SAID CONDUIT AND CONCOMITANTLY CAUSING SAID CONDUIT TO BE CLOSED OFF FROM SAID CONTAINER; DISPLACING THE CONTENTS OF SAID CONDUIT WITH AN INERT LIQUID TO PROVIDE A STATIC HEAD PRESSURE IN SAID CONDUIT GREATER THAN THE PRESSURE IN SAID CONTAINER AND MAINTAIN SAID CONDUIT IN SAID CLOSED OFF CONDITION; AND THEREAFTER WITHDRAWING SAID PUMP FROM SAID CONDUIT. 